NAME
tracerx.pl - runtime call tracer for nginx
DESCRIPTION
Simple runtime call tracer. Uses profiling instrument functions and
symbol table to record and print calls. Useful for complex problems and
learning nginx internals.
Something similar can be done with gdb and lots of breakpoints, but
annoyingly slowly.
INSTALLATION
Download and compile nginx with "ngx_trace" module:
% ./configure --add-module=/path/to/ngx_trace && make
This will enable debug symbols and instrument functions for gcc. Next,
make sure binary works and can print its own version:
% ./objs/nginx -V
Prepare environment to run nginx from:
% mkdir mynginx
% mkdir mynginx/logs
% cp -r conf mynginx/
% cp -r html mynginx/
Edit your new "nginx.conf", make sure it runs single process in
foreground and uses ports that don't require privileges to bind to:
daemon off;
master_process off;
...
http {
server {
listen 5678;
...
I find it useful to print errors to stderr as well:
error_log /dev/stderr debug;
And now you can start playing with tracerx.pl:
% /path/to/ngx_trace/tracerx.pl ./objs/nginx -p mynginx
More useful: prints filename, line number, calls within http, event
modules, ngx_connection.c and ignores access.log messages:
% ./tracerx.pl -l -f 'core/ngx_conn|http/|event/' \
-i 'get_indexed_variable|_log_' \
./objs/nginx -p mynginx
SYNOPSIS
tracerx.pl [OPTIONS] COMMAND [ARGS]
OPTIONS
-l print filename, line number saved from "nm -l" and time offset
-s PATTERN
print calls matching specified regex pattern only
-c PATTERN
print calls matching specified regex pattern in yellow color
-i PATTERN
ignore calls matching regex pattern
-f PATTERN
print calls if filename matches pattern
-t show how much time it took to run each function in microseconds
-u show addresses of unknown functions
EXAMPLES
Show all calls within src/http and src/event modules:
% ./tracerx.pl -f 'src/http|src/event' ./objs/nginx -p mynginx
Show calls within http and ignore all calls containing _log_ in function
name:
% ./tracerx.pl -f 'src/http' -i '_log_' ./objs/nginx -p mynginx
AUTHOR
Alexandr Gomoliako <zzz@zzz.org.ua>
LICENSE
Copyright 2011 Alexandr Gomoliako. All rights reserved.
This module is free software. It may be used, redistributed and/or
modified under the same terms as Perl itself.